feat(calendar): add feed subscription, bulk export, share & Google Cal

- /api/kalender.ics SSR route: ICS feed of all calendar items (webcal-subscribable, Cache 1h)
- buildICSFeed() / downloadICSFeed() for multi-event ICS export
- googleCalUrl() deep-link pre-fills Google Calendar create form
- Web Share API per event (navigator.share on mobile, clipboard fallback on desktop)
  — "Kopiert\!" toast per event for 2s after clipboard write
- Actions bar (subscribe + bulk export) only rendered after onMount
  — Apple platforms: webcal:// link opens Calendar.app natively
  — All others: direct ICS download via <a download>

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/iconify-mdi-subset.generated.json

@@ -72,9 +72,15 @@
     "download": {
       "body": "<path fill=\"currentColor\" d=\"M5 20h14v-2H5m14-9h-4V3H9v6H5l7 7z\"/>"
     },
+    "google": {
+      "body": "<path fill=\"currentColor\" d=\"M21.35 11.1h-9.17v2.73h6.51c-.33 3.81-3.5 5.44-6.5 5.44C8.36 19.27 5 16.25 5 12c0-4.1 3.2-7.27 7.2-7.27c3.09 0 4.9 1.97 4.9 1.97L19 4.72S16.56 2 12.1 2C6.42 2 2.03 6.8 2.03 12c0 5.05 4.13 10 10.22 10c5.35 0 9.25-3.67 9.25-9.09c0-1.15-.15-1.81-.15-1.81\"/>"
+    },
     "calendar-search": {
       "body": "<path fill=\"currentColor\" d=\"M15.5 12c2.5 0 4.5 2 4.5 4.5c0 .88-.25 1.71-.69 2.4l3.08 3.1L21 23.39l-3.12-3.07c-.69.43-1.51.68-2.38.68c-2.5 0-4.5-2-4.5-4.5s2-4.5 4.5-4.5m0 2a2.5 2.5 0 0 0-2.5 2.5a2.5 2.5 0 0 0 2.5 2.5a2.5 2.5 0 0 0 2.5-2.5a2.5 2.5 0 0 0-2.5-2.5M19 8H5v11h4.5c.31.75.76 1.42 1.31 2H5a2 2 0 0 1-2-2V5c0-1.11.89-2 2-2h1V1h2v2h8V1h2v2h1a2 2 0 0 1 2 2v8.03c-.5-.81-1.2-1.49-2-2.03z\"/>"
     },
+    "calendar-plus": {
+      "body": "<path fill=\"currentColor\" d=\"M19 19V8H5v11zM16 1h2v2h1a2 2 0 0 1 2 2v14c0 1.11-.89 2-2 2H5a2 2 0 0 1-2-2V5c0-1.11.89-2 2-2h1V1h2v2h8zm-5 8.5h2v3h3v2h-3v3h-2v-3H8v-2h3z\"/>"
+    },
     "arrow-right": {
       "body": "<path fill=\"currentColor\" d=\"M4 11v2h12l-5.5 5.5l1.42 1.42L19.84 12l-7.92-7.92L10.5 5.5L16 11z\"/>"
     },